It has been agreed that the G.hnem will use OFDM and will have the ability to adapt to channel conditions. Further, it is well known that the signal-to-noise ratio (SNR) changes with frequency. Consequently, it is necessary to use receiver feedback to adapt the coding scheme and adapt the modulation scheme on different subcarriers. It may also be necessary to adapt the transmit power.
Periodic impulse noise often occurs on power lines due to the zero-crossings of the AC mains. This noise may be introduced, for example, by a triac or a zero-crossing sense resistor in a dimmer circuit. These periodic impulse noise pulses may interfere with the transmission of data in power line communication systems.